Republican U.S. Rep. Mike Coffman and Democratic challenger Andrew Romanoff on Tuesday night sparred on climate change, immigration, campaign finances and campaign attacks in a Denver Post debate that highlighted a clash of personalities as much as ideas.

Romanoff was fast on his feet and threw repeated jabs, while Coffman seemed hesitant to engage — a contrast to the pair’s previous debate, in Aurora in August. That time, when Romanoff would get under his skin, Coffman jabbed back, even raising his voice in lecture at one point.

Romanoff kept his arguments focused on the partisanship and gridlock of Congress and, at times, Coffman himself. Coffman seemed reserved and studious, going after Romanoff’s record as the speaker of the state House only near the end of the hour-long debate.

“I am running for Congress because I am optimistic about the prospects for our country to move forward despite the efforts of so many in Congress to hold us back, and you have some evidence of that on the other side of the stage tonight,” Romanoff said in his closing arguments.

He added, “We’re not going to get the progress we need from this Congress and, I’m sad to say, not from this congressman.”

Tougher in previous debates, Coffman was reserved for much of his time in Tuesday’s event, held in the auditorium at The Post building. Instead, he frequently brought up his service in both Iraq wars and his work as a small businessman, a former state treasurer and veteran congressman representing Colorado’s 6th Congressional District.

He said Romanoff has “a miserable (voting) record” with small businesses, as rated by the National Federation of Independent Business.

“What confidence can you give to small-business owners throughout the district that you’re going to be different as a member of Congress?” Coffman charged.

Romanoff said he rejected the premise of the question and that it was never his intent in the legislature to “achieve high scores with a particular card of an interest group.”

Coffman appeared to stumble on questions about climate change.

Asked whether humans contributed significantly to climate change, he responded that he did not think so.

Coffman quickly sought to clarify his answer, backtracking to say humans do contribute to climate change, but the magnitude of the influence is unclear.

“On the climate change issue, I just think the science is not quite settled. Does it have an impact? Yes,” Coffman said. “Do I know how much of an impact it has, man-made climate change? I don’t know. But I think we need to do everything responsible to bring down carbon emissions. Sometimes, my worry is we go too far.

“What happens is we push, particularly manufacturing jobs overseas to a country like China, that has no environmental rules, and those products are made with greater carbon emissions than otherwise would have been made in the United States. So I think there has to be a balance to the issue here.”

Romanoff used a question on green-energy subsidies to return to the climate change issue and criticize Coffman on his answer.

“It’s especially revealing tonight because it’s plain to me that we are never going to take the action we need to address climate change if we don’t recognize the problem. Congressman Coffman made it clear tonight he does not recognize this problem despite the overwhelming scientific consensus about the origins of climate change.”

Throughout the debate, Romanoff and Coffman returned to women’s rights issues — Romanoff to press the issue and Coffman to defend his record. Romanoff cited Coffman’s past support for personhood ballot measures that would outlaw abortion and, critics argue, could imperil some forms of contraception. Coffman said he backed away from supporting personhood a couple years ago because such measures are too broad, with effects that made him uncomfortable.

But he reiterated more than once that he’s “pro-life” and defended his record on supporting access to birth control against Romanoff’s suggestions that such statements were muddied by Coffman’s past votes.

The debate, which is over representation of the district that included the 2012 Aurora theater shooting and the 2013 murder-suicide involving two students at Arapahoe High School, also featured questions about gun control.

“What law would have stopped those killings?” Romanoff said. “The tough lesson, the conclusion that’s painful to draw, is in some cases is none. We can’t stop every crime. We can’t prevent every tragedy. But that recognition does not relieve us of the responsibility to spare as many families as we can the anguish so many in our districts have suffered.”

Coffman said it was too early to weigh the effect of the gun laws Colorado enacted last year, but he said things could be done to make the mental health system better able to alert authorities to danger signs, such as those presented in the case of accused Aurora theater shooter James Holmes. He said a bill before Congress would do that.

During a question about vouchers, which Romanoff opposes for private schools, Coffman mentioned Romanoff’s Ivy League background.

“Speaker Romanoff, in debates you’ve often pointed out sometimes that you’ve had a privileged life, God bless you, went to private prep school and on from there,” Coffman said.

“It’s actually you, Congressman, who has spent the bulk of this campaign talking about very little else — my school, my education, my family,” Romanoff said a few moments later, chuckling. “Thank God you haven’t picked on my dog yet.”

Both candidates took exception to the way they were being portrayed by the opposition campaigns.

Asked what the biggest falsehood told about him, Romanoff replied, “How much time do you have?”

He said he had refrained from engaging in personal attacks and vowed to fire any of his staffers who did.

Coffman replied, “I think it’s about being honest, and your ad out there is not honest.”

Romanoff asked, “Which part?”

Referring to the ad characterizing his positions on personhood and birth control, Coffman said, “I think you know which part it is. I have the floor right now, and I think it’s a fundamental problem.”

The Post’s debate is the third formal debate in the race, which is one of the most competitive in the nation this year.

After Tuesday’s debate, Romanoff supporters talked up his aggressive style. Coffman’s campaign manager, Tyler Sandberg, said Coffman stood back sometimes because he was confident in his position in the race, based on internal polling that Sandberg wouldn’t disclose.

At least four more debates are scheduled in the 6th District race before the Nov. 4 election.

Denver Post staff writers John Frank and Lynn Bartels contributed to this story.

Denver Post staff writers John Frank and Lynn Bartels contributed to this story.

Highlights between U.S. Rep. Mike Coffman, a Republican, and the Democrat who wants to unseat him, former House Speaker Andrew Romanoff, in Tuesday’s debate:

Denver Post: “Mr. Romanoff, what is the biggest falsehood your opponent is repeating about you and how is it untrue?”

Romanoff: “How much time do you have?”

Coffman on same-sex marriage:

“Certainly I believe marriage is between a man and a woman. Ultimately it’s going to be up to the voters of Colorado to make that decision. I will respect as a member of Congress whatever decision that they make.”

“Just left CD-6 debate. I have never seen another candidate so thoroughly dismantled in a political debate. Bad night for Coffman”

@Jason_Bane, liberal blogger

“COFFMAN WINS AGAIN: Romanoff Reeks Of Desperation”

@COPeakPolitics, conservative blog

“Coffman, calm and refusing to engage, is debating like a candidate with a lead. Romanoff, much more animated/aggressive.”

@EliStokols, Fox 31 reporter

Coffman mentioned at least six times his service in the military, including when asked about President Barack Obama’s strategy to target the Islamic State.

“My concern is how do you define boots on the ground?” Coffman asked. “I define it, as a former United States Marine Corps officer, as not putting conventional forces on the ground needed for new realities.”

Romanoff was asked about moving from Denver into the newly drawn 6th District, which now includes all of Aurora.

“Frankly, Congressman Coffman testified against the creation of the 6th Congressional District, and he suggested in testimony he didn’t want parts of Aurora included in his district. He didn’t want the responsibility of representing this diverse, highly competitive, evenly divided district,” Romanoff said.

“I would be happy to relieve you that responsibility, congressman.”

Coffman later responded:

“If I say that you moved into the district not because you want to live in Aurora but because you want to live in Washington D.C., what is not true about that?” he asked.

Yes/no questions

During Tuesday’s debate, The Denver Post asked U.S. Rep. Mike Coffman and Democratic challenger Andrew Romanoff a series of yes-or-no questions:

1. Have federal grants to police departments for the purchase of tanks, weapons and other heavy equipment made local police too militarized?

Coffman: Yes. Romanoff: Yes.

2. Do you support federal action to provide clear rules for legal marijuana businesses to gain access to banking?

Coffman: Yes. Romanoff: Yes.

3. Should Colorado recognize same-sex marriage?

Coffman: No. Romanoff: Yes.

4. Do you support Colorado’s ban on same-sex marriage?

Coffman: Yes. Romanoff: No.

5. Is the House right to pursue a lawsuit against President Obama for executive overreach in delaying the employer mandate in the Affordable Care Act?

Coffman: Yes. Romanoff: No.

6. Do you believe humans are contributing significantly to climate change?

Coffman: No. Romanoff: Yes.

7. Do you think we can reverse climate change?

Coffman: No. Romanoff: Yes.

8. Do you support reducing the high U.S. corporate income tax rate to bring it more in line with other countries with which we compete?

Coffman: Yes. Romanoff: Yes.

9. Should the government, as Warren Buffett suggests, create a minimum tax for high incomes to prevent the wealthy from paying lower taxes on their investment income than many Americans pay on income taxes?

Joey Bunch was a reporter for 12 years at The Denver Post before leaving to join The Gazette in Colorado Springs. For various newspapers he has covered the environment, water issues, politics, civil rights, sports and the casino industry. He likes stories more than reports.

Jon Murray is an enterprise reporter on The Denver Post's government and politics team, with a focus on transportation. He previously covered Denver Mayor Michael Hancock and city government. A Colorado native, he joined The Denver Post in 2014 after reporting on city government and the legal system for The Indianapolis Star.